EFFECT OF VARIOUS LEVELS OF T-2 TOXIN IN THE IMMUNE-SYSTEM OF GROWINGPIGS

Four groups of seven-week-old pigs weighing about 9 kg were fed for th ree weeks a prestarter that contained 0.5, 1.0, 2.0 or 3.0 mg/kg of hi ghly purified T-2 toxin, The average daily intakes of toxin by the pig s were 0.38, 0.81, 1.24 and 1.43 mg, respectively, The experimental an d control pigs were immunised with 5 ml aluminium hydroxide gel absorb ed purified horse globulin on the first and fourth days of the treatme nt period, Blood samples were withdrawn on days 7, 14 and 21 and used for the determination of the titre of anti-horse globulin antibody, fo r an in vitro lymphocyte proliferation test, using purified horse glob ulin, phytohaemagglutinin and concanavalin-h and for determinations of the immune complex, the cytotoxic reaction and the phagocytic activit y and phagocytic index of circulating granulocytes. The samples taken on day 21 were also used to determine the erythrocyte count, the mean cell volume of the erythrocytes, the haematocrit, the blood haemoglobi n concentration, the leucocyte count and the proportion of T lymphocyt es. At the end of the experiment samples were taken from the thymus, s pleen and mesenteric lymph nodes for histological examination, The die ts that contained 2 and 3 mg T-2 toxin/kg caused a significant decreas e in the red blood cell count, the mean corpuscular volume and the hae moglobin concentration, A significant decrease in the leucocyte count and the proportion of T lymphocytes was observed in all the treatment groups, There were also dose-dependent, significant decreases in antib ody formation and in the blastogenic transformation of lymphocytes, an d mild to moderate reactive processes were observed histologically in the lymphoid organs.